Heterogeneity in the Trinidad DDT-resistant strain and the QS susceptible strain of Aedes aegypti L. The isolation of highly resistant and highly susceptible substrains.

Investigating heterogeneity in response to DDT with 2 strains of Aedes aegypti, the author has compared DDT-resistance in the F(1) and F(2) progenies of single-pair matings of resistant with resistant (TRINIDAD) and susceptible with susceptible (QS) strains.Both strains showed heterogeneity; however, there was little overlap between the most tolerant QS progeny and the least resistant TRIN progeny. A substrain of very high resistance was isolated from a single TRIN progeny and one of very low tolerance from a single QS progeny.Between QS progenies there was wide variation in DDT-tolerance, due in part to an environmental component but in part also to a genetic component. Variation between progenies in the already very resistant TRIN strain was marked. However, a genetic component was shown by the fact that it was possible to select an exceptionally resistant TRIN substrain in one step by rearing from the most tolerant TRIN progeny.